Stories, in games, novels, films, and all media alike, help us understand our world. Stories provide an escape from the real world, but they also reflect reality. They provide situations that may previously have been unimaginable, leading us to think about concepts in different ways. We learn through stories, we construct our mental model of the world through them.In this dissertation, I investigate the use of storytelling techniques in the domains of interactive storytelling and serious gaming. The field of interactive storytelling attempts to create and analyse systems that provide an interactive experience to users: the latter can influence the plot of story as it is being told. Serious gaming is concerned with the use of games for purposes other than only entertainment; in this dissertation, I investigate serious games with educational purposes. In both domains, I inspect how both human users and virtual agents (artificial, autonomous entities) can perceive stories.In Part i of this dissertation, I present my main thesis: the meta matters when interacting with interactive storytelling systems and serious games. All stories and games take place in a context: they take place in virtual worlds embedded within the real world. This concept is captured by the term magic circle. Virtual worlds are not separated from the real world; they are interconnected. Moreover, events and perceptions in the real world influence people's behaviour in the virtual world and vice versa. My research revolves around the use of such meta-information to improve experiences with interactive storytelling systems and serious games.In Part ii of this dissertation, I delve into the field of interactive storytelling, specifically focusing on the Virtual Storyteller (vst) and its successor, the Interactive Storyteller (ist). The vst provides users with an emergent narrative: stories are generated based on the interactions between virtual agents which play characters in the story. In the ist, users can take control of one of the characters, substituting a virtual agent, and influence how the story plays out. I first investigated how the meta matters to these systems by analysing interactions between pairs of children and the ist. This analysis showed that children, apart from only enacting in-character (ic) behaviour, actively go meta to reason about their plans and discuss their experience amongst each other (out-of-character behaviour, ooc). We created a scheme that allows for the annotation of this communication to discern the types of ic and ooc behaviour. With this scheme, we could see how the children's perspectives toward their interaction changed over time.Using the vst, we investigated how the meta can matter to its virtual agents. The generation of stories in the vst relies on the characters in the story world performing actions that advance the story. However, this does not necessarily entail that characters will take those actions. For example, if they can go about their way and never meet each other, possible conflicts can be avo...